The iPhone keyboard maker says BlackBerry's patents are invalid and the company doesn't own the concept of a keyboard

Typo Products, the start-up being sued by BlackBerry over an iPhone keyboard add-on, has come out swinging against a demand that its product be taken off sale in the U.S.

The company, which has garnered attention in part because it's backed by TV and radio personality Ryan Seacrest, submitted a 26-page argument to a California court late Wednesday against BlackBerry's demand for a preliminary injunction preventing sales of its keyboard.

BlackBerry's request, made in January when it launched its lawsuit, is a common one in such cases.

For it to succeed, BlackBerry has to convince the court that a number of conditions have been met: that it would probably win the case, that it would suffer "irreparable injury," that such injury would outweigh the damage to Typo from the injunction, and that it would be in the public interest.

Typo, not surprisingly, argued in the U.S. District Court for the Northern District of California that BlackBerry's complaint doesn't satisfy any of those conditions.

The company said BlackBerry's patent claims are invalid, that it won't suffer serious harm because its products aren't selling that well anyway, and that it has focused on the enterprise market while Typo is targeting consumers.

"BlackBerry seeks a monopoly on keyboards for any device. Regretfully, however, small keyboards with nearly identical layouts as the one 'claimed' by BlackBerry have been around since the mid-1980s," Typo said in its filing.

BlackBerry's original complaint didn't dispute the ability of competitors to make products with keyboards but rather the numerous similarities it alleged there are between the "iconic design" of its keyboard and the Typo keyboard.

"No one looking to buy a BlackBerry phone, because of an alleged 'resemblance,' would buy a case with a physical keyboard instead. Typo keyboards are sold on Typo's website, cost $99.00, and are for people who already own an iPhone. BlackBerry phones are sold on its own website, cost $549.00, and require activation from a cell phone carrier. No consumer will be confused," said Typo.

The filing also revealed a little about Typo's current business.

It said it had invested US$1.4 million in the development of the keyboard and had so far sold 4,000 of the devices. Its maximum monthly production is currently at 10,000 keyboards.

BlackBerry brushed off the company's assertions.

"The positions expressed in Typo's opposition lack merit, and BlackBerry will contest those issues vigorously in its reply," it said in a statement to IDG News Service.

"BlackBerry has invested years of research and development and millions of dollars to create the world's best mobile keyboard experience. We are proud of our keyboard designs and technology and will vigorously protect our intellectual property against any company that infringes our rights or attempts to copy our unique designs and patented technology," the company said.